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NASA Trumps Star Trek: Ion Drive Live!

Thrust_panels We're one step closer to Star Trek, with NASA successfully testing an experimental Ion Drive in Earth orbit.  In fact, since the Enterprise only had thrusters for low-speed maneuvers, this means we've got something even the guys with Warp Drive didn't think of. 

It turns out that carrying tanks of volatile chemicals on your space ship and setting fire to them every time you want to move has a few problems.  Just ask Apollo 13.  And once you run out, that's it.  The Ion Drive instead operates electrically, carrying tanks of utterly inert Xenon gas - a "noble gas", so called because you could poke its mother in the face with matches and it won't catch fire.

You'll still run out awful fast if you just squirt gas to move like some kind of interstellar balloon, which is why the Ion Drive uses electrical acceleration.  An electric field is used to strip the Xenon of electrons, rendering it positively charged, then accelerate them out of the engine.  This gives a tiny amount of gas a much larger momentum, and by Newton's laws, an equal but opposite change in momentum is imparted to the spacecraft.

The resulting acceleration is tiny, but constant, and can be maintained entirely under solar power - in other words, running the engines is now free.  The first probe to use this system is the GOCE satellite, the Gravity field and steady-state Ocean Circulation Explorer.  GOCE must fly in a dangerously low orbit to gather data with its fantastically accurate gravity sensors.  So low that friction with the outer atmosphere will drag it down into an early, and remarkably fiery, grave - unless it's equipped with a revolutionary new engine.

The Ion Drive will operate to cancel out the Earth's effects on the satellite, keeping it in a constant balance between electrically powering out and plunging in.  The Ion Drive isn't limited to station-keeping, however - small but solar-powered accelerations are perfect for interplanetary, or even interstellar missions.  The GOCE engines can provide 20 milliNewtons of thrust - for a one-ton satellite, that's an acceleration of less than the width of a human hair per second squared, which is less than impressive.  Unless you keep it on for a month, say, and end up moving at four kilometers a second - and with a little work, you can refuel anywhere there's an atmosphere.

Ion Drive


It's about time this got some real world action. It's acceleration is abysmal, but once it gets going it can keep going for years.

A big step in the right direction to get us to places a little more ambitious than the moon.

I imagine ships will still carry chemical fuel thrusters for emergencies and potential sudden course corrections. Nothing about this engine is about fast reactions, which can be a problem if you need to dodge some stray asteroid.

NASA? GOCE is an ESA spacecraft with a UK-built ion drive. You could have written about Dawn or Deep Space 1 as NASA ion vehicles. But not GOCE.

.. I think they had ion drive in Star Trek ( seem to recall it being mentioned in Voyager at some point ? ). Maybe its "ion thrusters" or something.

Actually, I believe the Tie Fighters in Star Wars use Ion Drives....

Right. Star Wars, not Star Trek. T.I.E. = Twin Ion Engine.


Ion Drive? Yes, it's an ion drive, but its thrust power is so low that it takes days and weeks to accelerate, not seconds, so it's not much of a triumph over anything else.

I disagree, Graham.

This could prove useful on satellite missions to other planets. You could use rocket boosters and gravitational slingshot methods to get up to speed, but then use ion drives to make minute adjustments on the way there.

That and the technology will only get better, of course.

First of all, graham, it's not its thrust that makes it special. it's the fact that it is so energy efficient. Like the article said, it can run for years on a single tank of gas.
Secondly, this isn't new. Didn't nasa launch an ion drive-powered probe a few years ago? I know it was developed at least five or six years ago. I remember my dad showing it to me at home, so that was at least before i left for college.

Uh not to be a real nerd but that pic is from star wars not star trek.
( epi.3 when the crash the large ship at start of movie)

yeah I'm a nerd!

Isn't that screen cap from Revenge of the Sith?

Yeah, I was about to point out the image used here is from Star Wars: Episode III... luckily a fellow nerd pointed out the T.I.E

Hughes Aircraft Company had been testing the ion propulsion engine at their Space Simulation Laboratory in El Segundo California since the 1970's. It's noting new.

There was already a mission involving an ion engine over 5 years ago, called Deep Space 1

It wasn't in Earth orbit though.

This is not new technology, Ion "DRIVE" or Ion Thrusters are used quite a bit in earth orbit and for Space missions. We still have alot to go before we can say we are better than Star Trek at something.

20 mN of trust for a 1000 kg mass gives an acceleration of 2e-5 m/s^2. A month is around 2.6e6 seconds, yielding a speed of 2e-5 * 2.6e6 = 52 m/s, or around 190 km/h.

Not 4 kilometers per second.

I hope they experimented with different Ions to see which ones accelerate differently

Wow, stunning. Who would have thunk it??


The ion drive idea goes back to the 1930s. I remember as a kid reading a story from then by John W. Campbell Jr. that used it.

This is old technology. It doesn't get anybody any further in space travel. It's just another method of conventional acceleration of mass. No time warps or physics breakthroughs here.

The bottom line is that, understanding that no matter can travel faster than light speed, and given our ratio of life span to the distance to the nearest possibly inhabitable planets, there's no way we'll ever get outside of our solar system, unless somebody figures out how to get from point A to point B without displacing the spacial distance between them. This breakthrough would make Einstein's theory of relativity like child's play.

My dad worked on ionic satellite station keeping engines a number of years ago. They used teflon instead of inert gas, and arced electricity across them to ionize the material and accelerate it.
I believe people also also uses hall effect engines for this as well.

@engineer. Wrong equation. Use 1/2at^2

If you're gonna play all superior, get it right eh?

This is a bit of old news. NASA has an ION drive on a craft that was launched in 2004. This craft also had auto navigation correction system as well. It also had a 3rd brand new technology on it as well but I can't remember what it was.

@headjam: 1/2at^2 is displacement, not speed (notice the units will be m/s^2 * s^2 which is m)... "An engineer" got it right. The formula for velocity is V(t) = Vo + a*t (where Vo is initial velocity, a is acceleration and t is time accelerating).

Think twice before playing all superior eh?

The only reference to ion drives ("Either an atomic pile a hundred miles across...or ion power." as Scotty once phrased it) in Star Trek I'm aware of was in 'Spock's Brain,' possibly the very worst episode of the series. The writer clearly didn't know what it was all about. (I'm not sure that attributing ion drives to the dogfight maneuvers in Star Wars can be taken too seriously, either.)

And the nature of the 'thrusters' in Star Trek was never explained either (they might not be chemical either, you know) so it's kind of hard to compare to the performance of a real system...

And, as noted, this isn't the first use of an ion engine in space. However, ESA has recently made signifigant improvements to ion engine efficiency:

All they need now is a super conducting flux capacitor to act as an amplifier for the output. Then you'll see an engine that can go somewhere. Fast.

Hey, it works in the movies!

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